On October 1, it was announced that Dick Irvin had resigned as coach of Chicago due to ill health. He was suffering from bone cancer and had been ill for two years and had been hospitalized in Montreal. Irvin had been several days late to training camp. Tommy Ivan took over as coach. Later in the season, it was reported that Irvin had undergone minor surgery for anemia at Ross Memorial Hospital. Irvin died on May 15, 1957.

Ted Lindsay, Detroit's star left wing, became the fourth player to score 300 career goals on November 18, when he picked up two goals in an 8–3 pasting of the Montreal Canadiens. The other players to reach this prestigious mark were Nels Stewart, Maurice Richard and Gordie Howe (who played opposite Lindsay for most of the latter's career).

On January 5, the Rangers and the Black Hawks played an afternoon game at Madison Square Garden where the Rangers beat the Black Hawks 4–1. This game was broadcast on the Columbia Broadcast System network (CBS). Glen Skov spoiled Lorne "Gump" Worsley's would-be shutout with a goal in the third period.

Montreal beat Toronto 2–1 at the Forum in Montreal on January 10 and moved into first place. The game was hard-fought and referee Frank Udvari found it necessary to rule with an iron hand that angered the fans. Fans thought he was calling chippy penalties against the Habs and deliberately failing to call hooking and holding penalties by the Maple Leafs. The blow-off came in the last two minutes of the game. Maurice Richard received a high-sticking penalty. At 18:14, knowing his Maple Leafs were in danger, Toronto coach Howie Meeker pulled goaltender Ed Chadwick for six attackers. Dick Duff scored the tying goal, and Richard went berserk and commenced a heated argument with Udvari, banging his stick on the ice. He might have attacked Udvari if his teammates hadn't restrained him. Fans threw programmes, paper cups, hats and other debris and the game was held up. When it did resume, Bernie "Boom Boom" Geoffrion set up Don Marshall for the winning goal with a mere six seconds left to play. Although the fans were pleased with the outcome, an angry hum commenced as the players and officials left the ice. Udvari had to be escorted to his dressing room by police and ushers. A large part of the crowd now directed its attention to NHL President Clarence Campbell seated in his box seat and he became the target of jeers and threats. The situation began to show some of the aspects of the Richard Riot of two years previous when Richard had been suspended for an attack on an official. It was at least 30 minutes before Campbell was able to leave under police protection.

Terry Sawchuk had been playing well and was a candidate for the Hart Trophy, when he came down with mononucleosis. He came back too soon and by January 16, he announced his retirement from hockey, a temporary one as he would be back in Detroit next season.

Glenn Hall wasn't as good as the previous season, but led the Detroit Red Wings to first place. Hall had played only two games prior to 1955–56, but had shown such promise Sawchuk was sent off.

At the start of this season, the NHL changed the way power plays work. Prior to this season, a team could score as many goals as they wanted in a two minute power play with the penalised player remaining in the penalty box. The NHL changed it so that when a goal is scored on a two minute power play, the power play finished. The reason for this was because the Montreal Canadiens were so dominant on the power play, the NHL needed a way of ensuring parity. The previous season saw the Canadiens score 26% of all the league's power play goals. Oddly enough, the number of power play goals league-wide actually increased from 251 to 265 after the rule changed. Montreal, though, scored 10 fewer power play goals.